In recent years, in view of preventing infection due to accidental needle stick, dull needles (hereafter, also referred to as luers or the like) have come into wide use as alternatives for sharp metal needles that have been used conventionally. Such a dull needle is used in combination with a port (hereafter, it will be referred to as a needleless port) into which the dull needle can be inserted, and the combination of a dull needle and a port is specially adapted.
When only a certain kind of luers can be exclusively used with a particular kind of needleless ports, those luers cannot be used for the containers and bags that have other kinds of ports, and do not have very high compatibility.
When it is difficult to have a luer syringe securely held after insertion, a luer lock syringe sometimes is used instead. There have been developments of needleless ports that each have such a structure into which any types of luer syringes and luer lock syringes that meet the normal ISO standards can be inserted. For example, the U.S. Pat. No. 6,089,541 discloses a port in which a deformable septum is disposed so as to be shiftable inside the main body, and the internal structure of the septum, besides the opening, is a hollow. When an insertion member such as a luer is inserted into the opening of the septum, liquid communication is established. In addition, in order to make it possible to insert a luer lock syringe as well, a male screw-thread for screw-fastening is provided in the vicinity of the opening of the main body.
The U.S. Pat. No. 5,699,821 discloses a port in which a deformable, oblong, and tube-shaped septum is disposed inside the main body so as to be slidable. When an insertion member such as a luer is inserted into the opening of the septum, liquid communication is established. The oblong, tube-shaped septum has a passageway therethrough, and in the natural state, i.e. before the septum is mounted in the main body of the port, the passageway is open. When the septum is mounted in the main body, the function as a septum is exerted by having the entrance (or the exit) compressed. In addition, in order to make it possible to insert a luer lock syringe as well, a male screw-thread for screw-fastening is provided in the vicinity of the opening of the main body.
The U.S. Pat. No. 5,474,544 discloses a port in which a deformable septum is mounted inside the main body so as to be expandable. When an insertion member such as a luer is inserted into the opening of the septum, liquid communication is established and the port is filled with the septum having been deformed, thereby preventing fluid leaks. In addition, in order to make it possible to insert a luer lock syringe as well, a male screw-thread for screw-fastening is provided in the vicinity of the opening of the main body.
The conventional needleless ports mentioned above, however, each have a complicated structure and it is difficult to eliminate the dead space therein. Since there is a space in which bubbles can remain, safety during blood transfusion or infusion has not been sufficient.
For example, a septum disclosed in the U.S. Pat. No. 6,089,541, has a hollow internal structure besides the opening, and the hollow acts as a dead space. It is difficult to remove the bubbles remaining in this dead space.
The deformable septum disclosed in the U.S. Pat. No. 5,699,821 is oblong and tube-shaped and therefore, there is a hollow between the entrance and the exit, which acts as a dead space. It is difficult to remove the bubbles remaining in the space.
As for the septum disclosed in the U.S. Pat. No. 5,474,544, when the septum is deformed inside the main body, the septum tends to have a hollow therein, and it is difficult to completely avoid formation of a dead space. Further, it is difficult to balance avoidance of a dead space with easiness of insertion of a luer or the like.
Among these difficulties, focusing especially on avoiding formation of a dead space, the U.S. Pat. No. 5,354,275 discloses an injecting unit that is to be used with a septum having a slit or a through hole and makes it possible to completely avoid formation of a dead space by structurally solving the problem of having a hollow when a luer or the like is inserted. The injecting unit, however, may cause the following problems.
In the structure disclosed in the U.S. Pat. No. 5,354,275, in which the septum has a through hole, when a pressure is applied to the inside thereof and the septum is pressed upward, since the hole is open in the normal state, the hole on the surface of the septum tends to open up easily. Thus, there is a possibility that airborne bacteria and the like stick to the open hole and the inside of the septum is contaminated.
In the structure disclosed in the U.S. Pat. No. 5,474,544, although the septum has a slit therethrough, no additional compressive force is applied in the direction orthogonal to the slit. In such a structure, since the slit is not compressed, there is a possibility that medicinal fluid or the like remains in the slit. In addition, it is difficult to provide a slit at an accurate position in a septum that has a large thickness.
As for the structures disclosed in the U.S. Pat. No. 6,089,541 and 5,699,821, the internal structure is a hollow besides the opening. It is difficult to perform a priming process with such a structure, and there is a possibility that remaining air that has not been removed in the priming process may be pushed into the tubes during a process of supplying mixed injections. Also, when injected liquid medicine remains in the structure, it is difficult to measure exactly how much medicine has been injected to a patient. Further, when blood is in the main tube, there is a possibility that thrombi are caused due to the stagnation inside the hollow area.